scholarly journals Analytical and Numerical Crack Growth Analysis of 1:3 Scaled Railway Axle Specimens

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 184 ◽  
Author(s):  
David Simunek ◽  
Martin Leitner ◽  
Jürgen Maierhofer ◽  
Hans-Peter Gänser ◽  
Reinhard Pippan
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Crack Propagation ◽  
Crack Growth ◽  
Optical Measurement ◽  
Residual Lifetime ◽  
Residual Stress State ◽  
Propagation Analysis ◽  
Load Tests ◽  
Stress States

This paper deals with experimental fatigue crack propagation in rotating bending loaded round bar specimens as well as an analytical and numerical analysis of the residual lifetime. Constant amplitude (CA) load tests are performed with the surface crack length being evaluated using an optical measurement system. Fracture surfaces are microscopically analyzed to determine crack growth in depth as well as the crack shape. In spite of identical testing conditions, the experimental results show some scatter in residual lifetime, which is mainly caused by different residual stress states. Although X-ray residual stress measurements reveal only minor values, a superposition of the residual stress state with the load-induced stress leads to a significant impact on the residual lifetime calculations, which explains the experimental scatter. Numerical analyses are conducted to consider the residual stress state and their effect on crack propagation by different options. Considering the residual stress distribution in depth within the residual lifetime assessment, the deviation to the most conservative experiment is reduced from +48% to +2%. In conclusion, the results in this paper highlight that it is of utmost importance to consider local residual stress conditions in the course of a crack propagation analysis in order to properly assess the residual lifetime.

Residual Stress Development in Laser Machined PVD-Coated Carbide Cutting Tools

2013 ◽  
Vol 768-769 ◽  
pp. 391-397 ◽  
Author(s):  
Bernd Breidenstein ◽  
Christoph Gey ◽  
Berend Denkena
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Cutting Tool ◽  
Cutting Tools ◽  
Machining Process ◽  
Laser Machining ◽  
Residual Stress State ◽  
Stress States ◽  
The Individual ◽  
Coated Carbide

Abstract. There is growing interest in laser machining as an alternative to abrasive processes for creating cutting tool micro geometries. This technology is also suitable for creating micro geometries on cutting edges of superhard cutting tools. The pulsed nanosecond lasers, which are commonly used for this type of application, induce a high thermal load in the tool. This heat is believed to result in tensile residual stresses at the cutting edge surface, which are generally unfavorable for cutting tool performance because of the tendency to crack formation and propagation. Different levels of compressive residual stress exist after each step (sintering, grinding, shot peening, etching and PVD-coating). From investigations of commercial processes for manufacturing PVD-coated carbide cutting tools it is known that the final residual stress state of the carbide subsurface is a result of superposition of the stress states resulting from the individual process steps. In contrast to that, a laser machining process is expected to produce tensile residual stress due to the heat input. The present work describes the influence of a process chain alteration for PVD-coated carbide cutting tools by a laser machining process on the residual stress state in the finished tools.

scholarly journals Influence of Steel Grain Size on Residual Stress in Grinding Processing

2010 ◽  
Vol 638-642 ◽  
pp. 2389-2394 ◽  
Author(s):  
Masahide Gotoh ◽  
Katsuhiro Seki ◽  
M. Shozu ◽  
Hajime Hirose ◽  
Toshihiko Sasaki
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Grain Size ◽  
Stress State ◽  
Mechanical Grinding ◽  
Fine Grained ◽  
Residual Stress State ◽  
Analysis Methods ◽  
Average Grain Size ◽  
Fine Grained Steels

The fine-grained rolling steels NFG600 and the conventional usual rolling steels SM490 were processed by sand paper polishing and mechanical grinding to compare the residual stress generated after processing. The average grain size of NFG600 and SM490 is 3 μm and 15μm respectively. Therefore improvement of mechanical properties for such fine-grained steels is expected, it is important to understand the residual stress state of new fine-grained materials with processing. In this study, multi axial stresses of two kinds of specimens after polishing and grinding were measured by three kinds of analysis methods including cos-ψ method. As a result, as for σ33, the stress of NFG was compression, though that of SM490 was tension.

About Residual Stress State of Castings: The Case of HPDC Parts and Possible Advantages through Semi-Solid Processes

2022 ◽  
Vol 327 ◽  
pp. 272-278
Author(s):  
Elisa Fracchia ◽  
Federico Simone Gobber ◽  
Claudio Mus ◽  
Yuji Kobayashi ◽  
Mario Rosso
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Casting Process ◽  
Ray Method ◽  
Premature Failure ◽  
Thin Walls ◽  
Residual Stress State ◽  
Semi Solid ◽  
Pressure Die Casting

Nowadays, one of the most crucial focus in the aluminium-foundry sector is the production of high-quality castings. Mainly, High-Pressure Die Casting (HPDC) is broadly adopted, since by this process is possible to realize aluminium castings with thin walls and high specific mechanical properties. On the other hand, this casting process may cause tensile states into the castings, namely residual stresses. Residual stresses may strongly affect the life of the product causing premature failure of the casting. Various methods can assess these tensile states, but the non-destructive X-Ray method is the most commonly adopted. Namely, in this work, the residual stress analysis has been performed through Sinto-Pulstec μ-X360s. Detailed measurements have been done on powertrain components realized in aluminium alloy EN AC 46000 through HPDC processes to understand and prevent dangerous residual stress state into the aluminium castings. Furthermore, a comparison with stresses induced by Rheocasting processes is underway. In fact, it is well known that Semi-Solid metal forming combines the advantages of casting and forging, solving safety and environmental problems and possibly even the residual stress state can be positively affected.

scholarly journals Analysis of the Influence of Surface Modifications on the Fatigue Behavior of Hot Work Tool Steel Components

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7324
Author(s):  
Thomas Wild ◽  
Timo Platt ◽  
Dirk Biermann ◽  
Marion Merklein
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Surface Integrity ◽  
Fatigue Behavior ◽  
Hot Forging ◽  
Surface Modifications ◽  
Bending Test ◽  
Fatigue Properties ◽  
Machining Processes ◽  
Residual Stress State

Hot work tool steels (HWS) are widely used for high performance components as dies and molds in hot forging processes, where extreme process-related mechanical and thermal loads limit tool life. With the functionalizing and modification of tool surfaces with tailored surfaces, a promising approach is given to provide material flow control resulting in the efficient die filling of cavities while reducing the process forces. In terms of fatigue properties, the influence of surface modifications on surface integrity is insufficiently studied. Therefore, the potential of the machining processes of high-feed milling, micromilling and grinding with regard to the implications on the fatigue strength of components made of HWS (AISI H11) hardened to 50 ± 1 HRC was investigated. For this purpose, the machined surfaces were characterized in terms of surface topography and residual stress state to determine the surface integrity. In order to analyze the resulting fatigue behavior as a result of the machining processes, a rotating bending test was performed. The fracture surfaces were investigated using fractographic analysis to define the initiation area and to identify the source of failure. The investigations showed a significant influence of the machining-induced surface integrity and, in particular, the induced residual stress state on the fatigue properties of components made of HWS.

Residual Stress State and Fatigue Behaviour of Laser Shock Peened Titanium Alloys

2006 ◽  
pp. 129-134
Author(s):  
I. Altenberger ◽  
Yuji Sano ◽  
M.A. Cherif ◽  
Ivan Nikitin ◽  
Berthold Scholtes
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Titanium Alloys ◽  
Fatigue Behaviour ◽  
Laser Shock ◽  
Residual Stress State

Hydration and radiation effects on the residual stress state of cortical bone

2013 ◽  
Vol 9 (12) ◽  
pp. 9503-9507 ◽  
Author(s):  
Patrick K.M. Tung ◽  
Stephen Mudie ◽  
John E. Daniels
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Cortical Bone ◽  
Radiation Effects ◽  
Residual Stress State

Pre PVD-Coating Processes and their Effect on Substrate Residual Stress in Carbide Cutting Tools

2010 ◽  
Vol 438 ◽  
pp. 17-22 ◽  
Author(s):  
Berend Denkena ◽  
Bernd Breidenstein
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Cutting Tools ◽  
Residual Stress State ◽  
Pvd Coating ◽  
Parameter Variations ◽  
Single Process ◽  
The Stability ◽  
Cohesive Damage ◽  
Coated Cemented Carbide

Cohesive damage of PVD-coated cemented carbide cutting tools is ascribed to the residual stress state of the substrate subsurface. The present paper shows the formation of the substrate residual stress in the process chain as well as the stability of the single process steps referred to the scattering of the residual stress values. Depth resolved residual stress measurements across coating and substrate subsurface show a layer in the substrate, where possibly tensile stress occurs, from where cohesive damage may be initialized during tool use. Results of experiments are presented, where the influence of parameter variations in pre coating processes on the residual stress state is investigated. The characteristics of compressive residual substrate stress during the final PVD-process is presented as well as a correlation between coating and substrate stress.

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